1. Technical Field
The present invention relates to an idling stop control system for a vehicle that automatically stops an idling of an engine in the case where an automatic stop condition of the engine is established and that automatically starts the engine in the case where an automatic start condition of the engine is established.
2. Related Art
Recently, in order to improve fuel economy and to decrease exhaust gas emission, various kinds of techniques concerning a function for stopping idling have been proposed and are in practical use. The function automatically stops an engine when operation of the engine is not required in a state such as while waiting for a traffic light to change, a train to pass, or a person to come, and then the function automatically starts the engine when operation of the engine is required. For example, Japanese Unexamined Patent Application Publication (JP-A) No. 2000-45819 discloses a technique of an idling control system for a vehicle, which calculates a relative speed of a preceding vehicle on the basis of a change of an inter-vehicle distance and a speed of the vehicle. The system determines whether the preceding vehicle stops or starts by checking on the calculated relative speed of the preceding vehicle and the speed of the vehicle provided with the system. When it is determined that the preceding vehicle stops and the vehicle also stops, a stop mode is automatically executed to stop the engine of the vehicle; and when it is determined that the preceding vehicle starts during the engine of the vehicle being in the stop mode, an idling start mode is automatically executed to restart the engine of the vehicle.
In the technique used in such as the idling control system disclosed in JP-A No. 2000-45819, the idling start mode is automatically executed to restart the engine when it is determined that the preceding vehicle starts to move (hereinafter, containing changes of an inter-vehicle distance and a speed) while the vehicle is at a stop under the stop mode. However, in the state the vehicle is under such a stop mode, if a pedestrian crosses a road, a bicycle moves, or a motorcycle slip through traffic in front of the vehicle, the idling control system may mistakenly determine, due to such moving objects, that the preceding vehicle starts to move. Thus, the stop mode is unnecessarily released, and as a result, the idling start mode may be repeatedly executed. Thus, if release of the stop mode is unnecessarily frequently executed, not only is it difficult to successfully improve fuel economy, but also the unnecessarily frequent ON/OFF of the engine may annoy the driver.